This invention relates to the packaging of circuits, and more particularly to the packaging of microelectronic circuits.
As the density of circuit elements, such as resistors, capacitors, and transistors, is increased in a microelectronic circuit, heat generated by the circuit elements during the operation of the circuit increases. This heat conducts through the chip on which the microelectronic circuit is fabricated and must be efficiently removed from the chip. Failure to efficiently remove the heat from the chip can result in catastrophic failure of the microelectronic circuit.
FIG. 1 is a cross-sectional view of prior art microelectronic circuit package 100. Microelectronic circuit package 100 comprises substrate 103, encapsulated solder balls 106, electronic chip 109, thermal interface material 112, integrated heat spreader 115, and sealant material 118. Substrate 103 is a fragile sandwich of conductors and insulators formed on a ceramic base. Encapsulated solder balls 106 provide a conductive path for signals routed between electronic chip 109 and substrate 103. Thermal interface material 112 is a cured epoxy and is capable of transmitting heat from electronic chip 109 to integrated heat spreader 112. Integrated heat spreader 115 is a complex machined device that efficiently dissipates heat into the air and is secured to substrate 103 by sealant material 118. The bond provided by sealant material 118 between integrated heat spreader 115 and substrate 103 hermetically seals the space enclosed by substrate 103 and integrated heat spreader 115.
Unfortunately, there are several problems with microelectronic package 100. First, integrated heat spreader 115 is a complex machined device that is expensive to manufacture. Second, thermal interface material 112 is a cured epoxy that takes a significant amount of time to cure, which slows the manufacturing process, and increases the cost of the package.
Other problems with microelectronic package 100 arise as the heat flow in electronic chip 109 increases. First, the mismatch between the coefficients of thermal expansion of integrated heat spreader 112, thermal interface material 112, and electronic chip 109, causes electronic chip 109 to tear away from integrated heat spreader 112 and generate voids and uneven heat flow in thermal interface material 112. Second, the mismatch between the coefficients of thermal expansion of heat spreader 112 and substrate 103 cause integrated heat spreader 112 to tear away from substrate 103, which breaks sealant material 118, destroying the hermetic seal and structurally damaging the fragile conductors and insulators of substrate 103.
For these and other reasons there is a need for the present invention.
An electronic chip package comprises an electronic chip, a slug thermally coupled to the electronic chip, and a mechanism capable of exerting a constant force on the slug.